Leakdown tester question
 

I just got a leakdown tester (the one sold by Pelican) and it has two gauges. The left gauge shows PSI and the right shows percentages (the gauge shows 20% to 100% leakage with colors indicative of low, moderate, and high leakage). Since the gauge on the right starts off at 20%, how will I read percentages that are small such as 2 or 3 percent? Would I be better off just replacing the right gauge with a numerical gauge like the left one? The right gauge seems worthless for a P- Car. Any suggetsions please....

I don't know about the Pelican gauge but I recently used a snap-on one, it had a single gauge marked 0-100% and a dial that was used to adjust the needle to 0% before the adapter was connected to the plug hole. My 3.3 read 4%-6% across all cylinders

You need to send that one back - they must have sent you the General Motors model...
Just kidding. The gauge I have used for years has two identical gauges that read from 0 to 110 psi. The 'Leakdown' is the percent difference between the two readings (i.e. if the left was 100 psi (your supply pressure) and the right 90 psi the leakdown would be 10 %).
I would be careful (and have a good understanding) with a right gauge marked in '%' because it will require a set psi on the left gauge (I am fairly certain).

The set that Steve refers to is very good as well with only a single gauge.
Good luck -

THanks for the help guys. I wasn't sure I could send the one I bought back but was able to. I am going to order another one - what types are you guys using?